Austin Leclaire, left, and his brother Max Leclaire, both have Duchenne muscular dystrophy. However, only Max is able to get treatment from a drug in a clinical trial.

SAXTONS RIVER — When her eldest son Austin was about 2 years old, Jennifer McNary noticed something was off. He could not kick a ball like boys his age and had greater difficulty walking.

Today, Austin, who turns 14 on Wednesday, uses a wheelchair because he suffers from Duchenne muscular dystrophy, a degenerative and eventually fatal disease.

His 10-year-old brother, Max, also has Duchenne muscular dystrophy. Unlike his brother, Max has access to the drug eteplirsen as part of a highly successful clinical trial. The drug targets the same gene mutation that is expected to eventually kill both brothers, though their long-term benefit from eteplirsen — if it is approved — is not yet known.

Over the course of the last year, thanks to weekly intravenous infusions of the drug, Max no longer has to use his wheelchair and can walk.

“It has absolutely changed his life,” McNary said during a phone interview last week. “He just learned to dance. He is doing the typical things a 10-year-old would do.”

She said they recently received a report from Max’s physical education teacher saying that Max was on the same level as the boys his age — a first for him.

“It was like a light switch went on and all the teachers are noticing,” said his stepfather, Craig McNary.

The McNarys are also raising four healthy children.

Austin was not allowed to participate in the trial because one of the inclusion criteria was to complete a six-minute walk. In the last year, he has become weaker, losing all upper body strength in the last couple of months.

NcNary recently petitioned the Food and Drug Administration to give the drug accelerated approval so that Austin can benefit from it. She has also launched an online petition which has garnered more than 13,000 signatures on change.org.

“Our hope is that FDA will approve the drug as quickly as possible,” she said. “There are a lot of kids that can benefit from this medicine.”

Duchenne muscular dystrophy is a genetic mutation that causes the loss of dystrophin, a large-structure protein which protects muscle fibers. Dystrophin is created by exon 52, which boys with the disease don’t have.

The disease affects one in 3,500 boys, with about 20,000 boys living with the disease in the United States and about 300,000 worldwide. It strikes between the ages of 3 and 5 as boys begin to progressively lose their ability to walk. Historically, by the time they hit their early teenage years they must use a wheelchair and begin to lose upper body strength. Later, breathing becomes more difficult, which will eventually lead to heart and lung failure.

There is no cure for Duchenne muscular dystrophy. Although doctors have used steroids to temporarily delay the inevitable loss of muscle strength, the disease is 100 percent fatal, McNary said.

“You expect that your son is going to die in his early 20s,” she said.

According to McNary, all 12 children who are participating in the clinical trial for eteplirsen at Nationwide Children’s Hospital in Columbus, Ohio, have seen some benefit with no side effects.

Eteplirsen is an exon-skipping drug that allows for the production of dystrophin. McNary said the drug could help up to 85 percent of boys with the disease.

“This is the first drug of its kind,” she said. “It’s important to get it approved. This medicine fits under accelerated approval.”

Sarepta Therapeutics, who manufactures eteplirsen and is pressing the FDA for approval, announced Friday that the drug has “maintained a statistically significant clinical benefit.”

“We are excited to see continued stability on the six-minute walk test with more than a year of follow-up where we would otherwise predict a significant decline,” Chris Garabedian, president and CEO of Sarepta Therapeutics, said in a statement.

McNary said when Austin was diagnosed at 3 years old and Max was diagnosed at three months, the neurologist basically told them to take the boys home and love them. Now, with the success of the drug, they are more hopeful for the future.

She is convinced that if the FDA approves the drug that has helped heal Max, it can also help Austin regain some of his strengths.

“Austin is understanding this. He is hopeful and knows that people are working really hard to get this drug,” McNary said.